The overall objective of this proposal is to investigate the mechanism of calcium-calmodulin stimulation of cerebral cortex adenylate cyclase. These studies will focus on three specific objectives. 1) Purification of adenylate cyclase from bovine cerebral cortex. Attempts will be made to purify adenylate cyclase on a large scale through a combination of DEAE Sephacel, and calmodulin, conconavalin A, and GTP Sepharase affinity chromatography. 2) Examine the role of guanine nucleotides in effecting calcium-calmodulin stimulation. We have recently shown that calmodulin stimulation could be restored to an insensitive form of adenylate cyclase by reconstruction with a dissociable protein subunit. We proposed that the dissociable subunit is the guanine nucleotide binding protein. We will further test this hypothesis by a series of reconstitution experiments. 3) Elucidate the subunit structure of adenlylate cyclase. The interactions of calmodulin, guanyl nucleotide binding, and catalytic subunits will be investigated by cross-linking studies with specifically labeled protein fractions.